Radio frames in a Long Term Evolution (LTE) system include a frame structure of Frequency Division Duplex (FDD) mode and a frame structure of Time Division Duplex (TDD) mode. As shown in FIG. 1, in the frame structure of the FDD mode, one 10 ms radio frame consists of 20 slots numbered as 0˜19 and with length of 0.5 ms, slots 2i and 2i+1 constitute a subframe i with length of 1 ms (wherein, 0≦i≦9). As shown in FIG. 2, in the frame structure of the TDD mode, one 10 ms radio frame consists of 2 half frames with length of 5 ms, 5 subframes with length of 1 ms are included in one half frame, and the subframe i is defined as a combination of two slots 2i and 2i+1 with length of 0.5 ms (wherein, 0≦i≦9).
In the above two frame structures, when a Normal Cyclic Prefix (Normal CP) is used, 7 symbols with length of 66.7 us are contained in one slot, wherein the CP length of the first symbol is 5.21 us, and the CP length of each of the rest 6 symbols is 4.69 us; and when an Extended Cyclic Prefix (Extended CP) is used, 6 symbols are contained in one slot, and the CP length of each symbol is 16.67 us.
Uplink-downlink configurations supported by each subframe are as shown in Table 1. Wherein, D represents a subframe exclusively used for the downlink transmission, U represents a subframe exclusively used for the uplink transmission, and S represents a special subframe used for 3 domains: Downlink Pilot Time Slot (DwPTS), Guard Period (GP) and Uplink Pilot Time Slot (UpPTS).
TABLE 1A schematic table of uplink-downlink configurations supported by each subframeDownlink-uplinkUplink-downlinkswitchover pointSubframe number #configurationsperiod012345678905 msDSUUUDSUUU15 msDSUUDDSUUD25 ms DSUDDDSUDD310 ms DSUUU DD DDD410 ms DSUUD DDD D D510 ms D SUDD DD DD D65 ms D S UU U DS U U D
From the above table, it can be seen that the LTE TDD supports a 5 ms uplink-downlink handover period and a 10 ms uplink-downlink handover period. If a downlink-uplink switchover point period is 5 ms, the special subframe will exist in two half frames; if the downlink-uplink switchover point period is 10 ms, the special subframe only exists in the first half frame; the subframe#0 and subframe #5 and the DwPTS are always used for the downlink transmission; and the UpPTS and subframes following the special subframe closely are exclusively used for the uplink transmission.
The LTE uses a Single Carrier-Frequency Division Multiple Access (SC-FDMA) way in uplink, and an uplink time domain symbol is an uplink SC-FDMA symbol. Formats of a Physical Uplink Control Channel (PUCCH) are divided into 6 formats: Format 1, Format 1a, Format 1b, Format 2, Format 2a and Format 2b, and 15 bits of original information can be transmitted at most. Each PUCCH occupies resources of 2 physical resource blocks in one subframe and occupies resources of 1 physical resource block in one slot.
In order to satisfy the requirements of International Telecommunication Union-Advanced (ITU-Advanced), a Long Term Evolution Advanced (LTE-A) system, as an advanced standard of the LTE, is required to support the wider system bandwidth (up to 100 MHz) and is required to be backward compatible with the existing standard of the LTE. Based on the existing LTE system, bandwidths of the LTE system can be combined to obtain the wider bandwidth, and this technology is called as Carrier Aggregation (CA) technology. The technology can improve spectrum utilization efficiency of an International Mobile Telecommunications-Advanced (IMT-Advanced) system and relieve shortage of spectrum resources, thereby optimizing utilization of the spectrum resources. LTE system bandwidths of the carrier aggregation can be regarded as a Component Carriers (CC), and each component carrier also can be called as one Cell, and it can be formed from the aggregation of n component carriers (Cells). Resources of an R10 User Equipment (UE) are composed of n cells (component carriers) of the frequency domain, wherein, one cell is called as a Primary cell, and each of the rest cells is called as a Secondary cell.
A format based on Discrete Fourier Transform Spread-Orthogonal Frequency Division Multiplexing (DFT-S-OFDM) is introduced in the LTE-A system, which is used to support that a UE with more than 4 bits performs feedback of ACKnowledgement/Non-ACKnowledgement (ACK/NACK) messages, and this new format based on the DFT-S-OFDM is called as a control channel format 3, and the PUCCH Format 3 uses an encoding way of Reed Muller (32, O) in the related art (i.e. an RM (32, O) encoding way), and 11 bits of information can be transmitted at most.
In a TDD system, one uplink subframe will correspond to multiple downlink subframes, and each downlink subframe has n cells, as shown in FIG. 3. According to different transmission modes, each cell can have one transmission block for transmission and also can have two transmission blocks for transmission. Due to the carrier aggregation, when one subframe corresponds to multiple cells in the frequency domain, the UE is required to perform feedback of downlink channel information of the multiple cells. Currently, since the bit capacity of the PUCCH feedback information is limited, it fails to perform simultaneous feedback of information of multiple cells of a corresponding downlink channel in one PUCCH, thus it needs to be allocated to different subframes for performing transmission, and this will cause longer feedback delay of the information, which goes against downlink dynamic scheduling of the base station and influences the system performance.